Sealing tongs

ABSTRACT

For attaching the ends of a metallic strap to each other there is used sealing tongs having a base fixed to a frame structure and provided with notches; at least two jaw elements fitted to the frame structure so as to slide transversally in relation to the strap and linearly towards and away from each other essentially on the same level as the strap, the jaw parts being adapted to be placed on the strap ends which are on top of each other, and on the surfaces of the jaw elements which come against the strap there are several spaced notches in the longitudinal direction of the strap; several punches on the opposite side of the base in relation to the strap ends to be joined and which are adapted to be moved towards the band and away from it for punching the strap ends when the punches are pressed into the notches in the jaw elements through the notches in the base; and means fitted to the frame structure for guiding the jaw elements and the punches and for actuating them synchronically in relation to each other so that the punches punch the strap seal essentially only when the jaw elements are in a position closest to each other.

United States Patent [19'] Back [111 3,811,481 [451 May 21, 1974 Primary ExaminerLowell A. Larson Attorney, Agent, or Firm-Brooks, Haidt & Hafner '57 ABSTRACT For attaching the ends of a metallic strap to each other there is used sealing tongs having a base fixed to a frame structure and provided with notches; at least two jaw elements fitted to the frame structure so as to slide transversally in relation to the strap and linearly towards and away from each other essentially on the same level as the strap, the jaw parts being adapted to be placed on the strap ends which are on top of each other, and on the surfaces of the jaw elements which come against the strap there are several spaced notches in the longitudinal direction of the strap; several punches on the opposite side of the base in relation to the strap ends to be joined and which are adapted to be moved towards the band and away from it for punching the strap ends when the punches are pressed into the notches in the jaw elements through the notches in the base; and means fitted to the frame structure for guiding the I jaw elements and the punches and for actuating them synchronically in relation to each other so that the punches punch the strap seal essentially only when the jaw elements are in a position closest to each other.

4 Claims, 8 Drawing Figures SEALING TONGS BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to scaling tongs for attaching the ends of metallic straps, especially strap irons, to each other.

2. Description of the Prior Art Various designs for sealing tongs are'known. Usually these known sealing tongs have jaws on opposite sides of the base, jaws which turn around a shaft parallel to the strap iron. When these jaws are closed they turn towards the strap iron and the base. If the base is much narrower than the strap iron, it can press into the strap iron, thereby punching the strap iron ends to be joined or possibly corrugating them. Altemately, the base may be provided with protuberances which press into the strap iron when the jaws force its ends against the base.

The object of the present invention is to provide sealing tongs which are improved compared to those previously known for attaching strap iron ends to each other more securely.

SUMMARY OF THE INVENTION The sealing tongs according to the invention comprise in combination at least two jaw elements fitted to the frame structure so as to slide transversally in relation to the strap and linearly towards and away from each other essentially on the same level as the strap, the jaw parts being adapted to be placed on the strap ends which are on top of each other, and on the surfaces of the jaw elements which come against the strap there are several spaced notches in the longitudinal direction of the strap; several punches on the opposite side of the base in relation to the strap ends to be joined and which are adapted to be moved towards the band and away from it for punching the strap ends when the punches are pressed into the notches in the jaw elements through the notches in the base; and means fitted to the frame structure for guiding the jaw elements and the punches and for actuating them synchronically in relation to each other so that the punches punch the strap seal essentially only when the jaw elements are in a position closest to each other.

DESCRIPTION OF THE DRAWINGS FIG. 1 shows a cross section of anadvantageous embodiment of the invention as seen from the side; to make the figure more illustrative, each side has been shown in a different extreme position and cut at a different point for the sake of clarity,

FIG. 2 is a section along line A-B in FIG. 1 and shows the jaw part of sealing tongs according to the invention in more detail,

FIG. 3 is the same jaw part as shown in FIGS. 1 and 2, seen from below,

FIG. 4 is a section along line CD in FIG. 3,

FIG. 5 shows a side view of a punch used in sealing tongs according to FIG. 1 (section E-F in FIG. 1),

FIG. 6 is a section along line G-I-I in FIG. 5 and shows a cross section of the punch,

FIG. 7 shows the sealed ends of the steel band as seen from above, and

FIG. 8 shows a perspective view of a part of the sealed steel hoop shown in FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As can be seen from FIG. 1, a base 2 has been fixed to the frame structure 1. The base has been provided with vertical notches 3 on the longitudinal middle plane of the base.- In this case, the base 2 has three successive spaced notches.

The ends 4, 5 of the strap iron 7 to be sealed have been placed one on top of the other on the free upper surface of the base 2. This surface is advantageously as wide as the strap iron 7.

The upper part of the frame structure '1 has been provided with two opposite slides or jaw elements 8, which can be slid on the same horizontal plane as the strap iron linearly towards and away from each other. In the right half of FIG. 1, the jaw element 8 is in its open position on the side of the strap iron 7, and in the left half,

the jaw element 8 is in its closed position in'which the two jaws are against each other.

The frame structure 1 has also been provided with a vertical cylinder 10 centrally under the base 2; The piston bar 12 of the hydraulic cylinder can then be moved vertically towards the base 2 and away from it. Arms 13 have been fitted at the end of the piston bar 12, on its opposite sides; suitably shaped guide surfaces '14 are provided at those ends of the arms which are farthest from each other.

In addition, horizontal shafts 16 have been attached to the frame structure 1, symmetrically on opposite sides of its center line, parallel to the strap iron 7; twinlever arms 15 have been fitted to the horizontal shafts 16 so that they can turn. The lower end of a twin-lever arm 15 is guided by means of a roller 19 or the like to follow the guide surface 14 in order to turn the lever arm 15 in a controlled mannr when the piston bar 12 moves in the vertical direction. .The upper end of a lever arm 15 has been fitted to the notch 11 in the lower surface of the jaw element 8 so that the pivoting movement of the lever arm can be transformed into a back-and-forth horizontal movement of the jaw element 8.

Several vertical punches 20 have been attached to the free end of the piston bar 12 on the center line of the sealing tongs, one under each notch 3.

As can be seen in more detail from FIGS. 2-4, the lower edges of those sides of the jaw element 8 facing each other have been cut so that the jaw elements 8 can be moved over the base to touch each other, in which case the upper surface of the said recess is against the upper surface of the topmost strap iron end 4, thus forming a stop against the punches 20. In those sides of the jaw elements 8 facing each other there are also three vertical notches 9 which, when projected to the base, correspond precisely to the shape of the cross section of the notches 6 in the base when the jaw elements are against each other. Thus, the notches 9 and 3 form a vertical channel for each punch 20.

In the position illustrated by the right side of FIG. 1, the sealing tongs are open, in which case the piston bar 12 is at its lowest position and the jaw elements 8 are farthest from each other, thus making it possible to place the strap iron ends to be joined on top of each other on the base 2. When the piston bar 12 moves upwards, the guide surfaces 14 and punches attached to it move simultaneously at the same speed. The punches 20 press into the notches 3 in the base 2, but do not yet touch the strap iron. The guide surfaces 14 turn the twin-lever arms 15 while forcing their lower ends 18 to follow the upper parts of the guide surfaces 14 which are curved against each other. When the guide surfaces 14 rise vertically upwards, their curving parts force the lower ends 18 of the lever arms 15 away from each other, in other words, the upper ends 17 of the lever arms 15 towards each other. The upper ends work together with the jaw elements 8 and force these to approach each other. The upper surface of each jaw element '8 is then pushed onto the strap iron ends to be joined and form a stop against the punch 20. When the jaw elements 8 meet, the lower ends 18 of the lever arms 15 have moved to the vertical part of the guide surfaces 14, and then the guide surfaces'can move upwards in spite of the fact that the leverarms 15 no longer turn. Only-at this point of the piston bar 12 movement, are the punches 20 pushed from the notches 3 in the base 2 to above its upper surface and force part 6 of the material of the strap iron ends 4 and 5 into the cuts 9 in the jaw elements 8. I

As can be seen from the side view of the punch 20 shown in FIG. 5, its upper front and back edges have been slanted so that the punch is slightly higher in the middle than at the front and the back, in which case only the edges of the punch-cut the 'strap iron when the punch 20 presses into the strap iron 7. As can be clearly seen from FIG. 6, the cutting vertical edges of the punch 20 have been slanted in the middle, in which case the front side of the punch is.narrower than its back side. 4

When the ends 4 and 5 of the strap iron 7 to be joined are punched with the said punch, of which there are three, the result shown in FIGS. 7 and 8 is obtained. Owing to the convexity of the upper surface of punch 20, the part 6 which has been separated from the strap iron is also convex upwards, in which case the adjacent parts of the strap iron' 7 are respectively concave downwards to balance the forces present in part 6.

A strap iron seal thus out has proven very durable and secure.

The hydraulic cylinder 10 can be replaced by a suitable lever arm system to obtain manually operated sealing tongs. It is also clear that there may be more than two jaw elements or slides, in which case each jaw element pair can have its individual control and operating system.

What is claimed is:

l. Sealing tongs for attaching the ends of a metallic strap to each other, and having a base fixed to a frame structure and provided with notches and on which the straps ends are adapted to be placed one on top of the other, comprising in combination:

at least two jaw elements fitted to the frame structure so as to slide transversally in relation to the strap and linearly towards and away from each other essentially on the same level as the strap, so that when the jaw elements are closest to each other they overlie the strap ends which are on top of each other, and on surfaces of the jaw elements which come against the strap there are several notches spaced in the longitudinal direction of the strap;

several punches on the opposite side of the base in relation to the strap ends to be joined and which are adapted to be moved towards the base and away from it for punching the strap ends when the punches are pressed into the'notches in the jaw elements' through the notches in the base; and

means fitted to the frame structure for guiding the jaw elements and the punches and for actuating them synchronically in relation to each other so that the punches punch the strap seal essentially only when the jaw elements are in said position closest to each other.

2. The sealing tongs of claim 1, in which the means for guiding and moving the jaw elements and the punches comprise a hydraulic cylinder fixed to the frame structure on the oppositeside of the base in relation to the strap, the pistonbar of the cylinder. being adapted for movement perpendicularly against the base and away from it; guide surfaces fixed to the piston bar on its opposite sides; two twin-lever arms which pivot around a shaft parallel to the strap, fitted to the frame structure on opposite sides of the pistong bar, one end of the each of the lever arms co-operating with the guide surfaces and the other ends with the jaw elements to force them towards or away from each other when the piston bar has been fitted to move towards the base or away from it, and the punches, also fitted to the piston bar perpendicularly in relation to the base and opposite to its nothces, being of such a length that they are pushed out from the cuts of. the base'essentially only when the jaw elements are in a position closest to each other and into the notches in the jaw elements only at their upper extreme position.

3. The sealing tongs of claim 2, in which the ends of the guide surfaces facing the jaw elements curve inwards towards each other in order to force the lever arm ends which co-operate with the guide surfaces away from each other and to force the-other ends towards each other when the piston bar and guide surfaces move towards the base, and the remaining part of each guide surface is parallel to the piston bar in order to keep the lever arms and the jaw elements in place when the piston bar, the punches and the guide surfaces move further.

4. The sealing tongs of claim 1, in which the upper surface of each punch is curved when seen from the side and the punches are of such a length that their front and back edges are essentially on the same level as the upper surface of the base when the punches are at their highest position, in which case only the curving side edges of the punches cut the strap and bend its cut part into an arch. 

1. Sealing tongs for attaching the ends of a metallic strap to each other, and having a base fixed to a frame structure and provided with notches and on which the straps ends are adapted to be placed one on top of the other, comprising in combination: at least two jaw elements fitted to the frame structure so as to slide transversally in relation to the strap and linearly towards and away from each other essentially on the same level as the strap, so that when the jaw elements are closest to each other they overlie the strap ends which are on top of each other, and on surfaces of the jaw elements which come against the strap there are several notches spaced in the longitudinal direction of the strap; several punches on the opposite side of the base in relation to the strap ends to be joined and which are adapted to be moved towards the base and away from it for punching the strap ends when the punches are pressed into the notches in the jaw elements through the notches in the base; and means fitted to the frame structure for guiding the jaw elements and the punches and for actuating them synchronically in relation to each other so that the punches punch the strap seal essentially only when the jaw elements are in said position closest to each other.
 2. The sealing tongs of claim 1, in which the means for guiding and moving the jaw elements and the punches comprise a hydraulic cylinder fixed to the frame structure on the opposite side of the base in relation to the strap, the piston bar of the cylinder being adapted for movement perpendicularly against the base and away from it; guide surfaces fixed to the piston bar on its opposite sides; two twin-lever arms which pivot around a shaft parallel to the strap, fiTted to the frame structure on opposite sides of the pistong bar, one end of the each of the lever arms co-operating with the guide surfaces and the other ends with the jaw elements to force them towards or away from each other when the piston bar has been fitted to move towards the base or away from it, and the punches, also fitted to the piston bar perpendicularly in relation to the base and opposite to its nothces, being of such a length that they are pushed out from the cuts of the base essentially only when the jaw elements are in a position closest to each other and into the notches in the jaw elements only at their upper extreme position.
 3. The sealing tongs of claim 2, in which the ends of the guide surfaces facing the jaw elements curve inwards towards each other in order to force the lever arm ends which co-operate with the guide surfaces away from each other and to force the other ends towards each other when the piston bar and guide surfaces move towards the base, and the remaining part of each guide surface is parallel to the piston bar in order to keep the lever arms and the jaw elements in place when the piston bar, the punches and the guide surfaces move further.
 4. The sealing tongs of claim 1, in which the upper surface of each punch is curved when seen from the side and the punches are of such a length that their front and back edges are essentially on the same level as the upper surface of the base when the punches are at their highest position, in which case only the curving side edges of the punches cut the strap and bend its cut part into an arch. 